The procedure where an engine driver and a signalman exchanged one single line tablet applicable to the section of line just traversed for another one authorising entry to the next section of line ahead.

A steam locomotive that carries its own water supply, rather than towing a separate vehicle for the purpose (often called a tender). Usually indicated by a ‘T’ appended to wheel arrangements when describing locomotives (e.g. 0-6-0T).

A valve actuating mechanism used in some early types of valve gear. An oscillating rod would have one or more dogs connected to the rod, each of which would make contact with and move a lever at a pre-determined point of the rod’s travel. The movement of the lever would then open or close a valve.